The proposal addresses a general objective of central importance in current biophysics-namely, to determine those structural and dynamic features of phospholipid bilayers that govern the distribution and function of membrane-bound proteins. The general objective will be approached through three specific aims: 1) To determine whether integral membrane proteins partition into regions of particular chemical structure or physical order in a lipid mixture. 2) To determine how the above partitioning characteristics effect the function of membrane-bound enzymes. 3) To determine phospholipid conformation in the vicinity of membrane protein. The proteins to be used are glycophorin, a well-characterized structural protein from the erythrocyte membrane, and Ca2+-ATP ase from rabbit sarcoplasmic reticulum, a membrane-bound enzyme with several well-defined functions. The primary structural methods to be used to address the specific aims are Raman and Fourier Transform Infrared Spectroscopy. Purified proteins will be reconsituted into binary phospholipid mixtures, which will have been selected to mimic the phase properties of natural membranes and to be amenable to detailed spectorscopic analysis. The conformation of each phospholipid component will be determined in order to see which component is more influenced by protein (Aim 1). Parallel enzyme activity measurements and structural analyses will be used to address Aim 2. Lipid melting curves as determined by vibrational spectroscopy will be obtained as a function of lipid/protein mole ratio in order to gain information about the conformation of lipid in the immediate vicinity of protein (Aim 3). Knowledge gained in the current work, will serve as a basis for understanding the mechanisms which govern structure-function relationships in biological membranes.